Enzyme-Controlled Reactions Experiment

Investigating Enzyme-Controlled Reactions

• Choose one variable to change at a time; control all other factors.
• Use a gas syringe to measure the volume of oxygen produced by catalase over time and repeat the experiment with different temperatures.
• Implement a negative control experiment to show no oxygen is produced without the active enzyme.

Control Variables

• Volume, concentration of substrate and enzyme solutions.
• Temperature and pH of solutions.
• Use water baths for maintaining constant temperature during experiments.
• Use buffer solutions to ensure consistent pH.

Calculating Rate of Reaction

• Rate of reaction is calculated using the gradient of a line on a graph.
• Initial rate is determined using a tangent drawn at the beginning of the curve.
• The gradient of the tangent shows the rate of reaction at a specific point.
• The initial rate will be highest because there are more enzyme-substrate interactions initially.

Explaining Rate of Reaction

• Rate of reaction slows as the substrate is used up, resulting in fewer collisions.
• The reaction stops when there is no substrate left.

### DNA and RNA Nucleotides

• Deoxyribonucleic acid (DNA) contains deoxyribose as the pentose sugar.
• Ribonucleic acid (RNA) contains ribose as the pentose sugar.
• A nitrogenous base and a phosphate group are also present in both DNA and RNA nucleotides.

Enzymes

• Proteins with a specific tertiary structure that act as biological catalysts.
• Active site: Complementary to a specific substrate, speeding up reactions by lowering activation energy.
• Location: Can be intracellular (inside cells) or extracellular (outside cells).
• Importance: Crucial for Determining cell and organism structure.

Induced Fit Model

• Replaced the Lock and Key Model, which proposed perfect enzyme-substrate complementarity.
• Active site flexibility: The shape of the active site changes slightly upon substrate binding to become fully complementary.
• Enzyme-Substrate Complex Formation: This complex puts stress on bonds or forms new bonds in the substrate, facilitating the reaction and lowering activation energy.

Temperature

• Kinetic Energy: Higher temperature leads to increased enzyme and substrate kinetic energy, resulting in more frequent and successful collisions and enzyme-substrate complex formation.
• Denaturation: Above the optimum temperature, enzymes become denatured. Excessive kinetic energy breaks hydrogen and ionic bonds between amino acid R groups, altering the active site shape and preventing substrate binding.
• Reversibility: Low temperature effects on enzyme activity are reversible, but high temperature denaturation is irreversible.

pH

• Denaturation: Enzymes are denatured both below and above the optimal pH.
• Ionic and Hydrogen Bond Disruption: H⁺ (acidic) or OH⁻ (alkali) ions interfere with hydrogen and ionic bonds between amino acid R groups, changing the active site shape.

Enzyme or Substrate Concentration

• Collision Frequency: Increasing either enzyme or substrate concentration increases the frequency of collisions between them, leading to more enzyme-substrate complexes.
• Saturation: Eventually, all available active sites are filled, or substrate concentration becomes limiting, leading to a plateau in the reaction rate.
• Graphs: The rate of reaction against temperature and pH is shown as bell-shaped curves, peaking at the optimum values. The curves demonstrate a maximum reaction rate that decreases as pH or temperature move away from the optimal levels. Denaturation is indicated by the downward trend in the curves beyond the optima.
• Diagram: A diagram illustrates the enzyme-substrate interaction process, showcasing the formation of the enzyme-substrate complex, the induced fit concept, and the release of products.

This quiz explores the principles and techniques used in enzyme-controlled reactions, including how to manipulate variables and measure reaction rates. It covers the importance of controlling factors like temperature and pH, as well as utilizing graphs to calculate reaction rates. Test your understanding of fundamental concepts in biochemistry.